Below is a round-up of the birth announcements from British newspapers. Sources include a national paper (The Telegraph, The Times) and a broad range of local newspapers from across England, Wales, Scotland and Northern Ireland.
Sibling names are in brackets. No official surnames are included; any name ending in a surname is actually a middle name.
Boys:
Albert George
Alfred Quentin James
Arlo Edward (Archie Thomas Peter)
Attikai Atlas Alphonso (Indus)
Caleb Alfie (Roxy Ava)
Casimir Charles Atticus
Elliot Rowell
Emile Loup Désiré
Frederick Ralph (Willamina Poppy)
James Andrew Nigel (Celia Lucile & Cosima Vera)
Montgomery
Nicholas Guy Christian
Theo "Teddy"
Girls:
Alexandra Melissa
Annabelle Katherine (Sienna)
Ava Catherine
Celeste Bella Morgan (Meadow, Jemimah & Penelope)
Florence Emilia Rose
Harriet Matilda Jean
Indie Tabitha Rose
Leonora Rose (Willa Iris)
Lily Maeve (Olivia)
Miriam Ava (Wilfred James "Freddie" & Iris Elizabeth)
Shiloh Iremide
Theodora Marie Elizabeth
Twins:
James Robbie Nicholson & Grace Janet
I cross-reference older BAs to find the full names of the siblings, however often they are missing (especially the eldest siblings, or for half-siblings) which explains why you will sometimes see something like: George Henry (Lucy, Emma & Jack Arthur). "Lucy" and "Emma" may well have middle names as well; I simply cannot find them online.